Insufficient automobile tire pressure at least will result in awkward driving, such as more gas consumption, lower tire endurability and shorter tire operation life, and even worse, will cause a flat tire which endangers passengers' life and driving safety. A tire condition sensing apparatus can assist a driver at any time inside the car to check the tire conditions, such as tire pressure, tire temperature, etc., thereby effectively increasing vehicle safety.
Generally speaking, a tire condition sensing apparatus is mounted on a rim of a vehicle tire, and includes a housing accommodating a sensor and a power source such as a battery. The sensor can detect the conditions (such pressure and temperature) inside the tire, and then transmit tire internal condition signals to a receiver located outside the tire. The receiver further evaluates the tire internal condition signals and provides the information of tire internal condition to a driver via a display apparatus mounted on the vehicle.
When the aforementioned housing and a valve stem are connected, and are assembled on a rim of a vehicle tire, the valve stem extends out from a though hole located on a sidewall of the rim, and then is fastened to the sidewall by a nut. After the valve stem is fixed on the sidewall of the rim, if the angle between the valve stem and the housing is not proper, the housing cannot contact the rim bed and is hung in the air. The housing hung in the air will be vibrated by the centrifugal force due to tire spinning, thus disadvantaging stable driving. In some worse situations, the housing hung in the air will hit the rim, thus resulting in the problems of damaging the tire condition sensor received therein, breaking the housing, or the valve stem detached from the housing, etc. The housing fragments or the free valve stem are very like to pierce the tire, thus affecting driving safety. Hence, how to make the housing firmly seat on the rim has become quite an important issue.
On the other hand, sine there are quite a lot of rim types, based on the consideration of the safety for assembling the aforementioned tire condition sensing apparatus, the length of the valve stem or the fixing angle between the valve stem and the housing has to be changed with respect to different types of rims, thereby ensuring the stability of the tire condition sensing apparatus mounted on the rim. However, those design changes causes the increase of production cost and user inconvenience.
U.S. Pat. No. 5,844,131 discloses a tire pressure sensing apparatus including a housing having at least two base seat members for placing the apparatus on the wheel rim. U.S. Pat. No. 6,865,932 discloses a device for mounting a sensor on a motor vehicle wheel rim, wherein two stop elements are arranged on both sides of the housing of the sensor for mounting the housing on the rim bed. While being applied to various types of rims, both patent references are not able to adjust the angle between the valve stem and the housing to fasten the sensor on the rim. On the other hand, their valve stems are fixed on the housing, so that the valve stem cannot be replaced with the one of proper length when the length of the valve stem does not fit in with the rim. Therefore, the aforementioned patent references cannot be suitable for use in various types of rims.
Hence, there is an urgent need to develop a tire condition sensing apparatus and a mounting method, thereby adjusting the angle between the valve stem and the housing; and replacing the valve stem with the one of different length, thus effective improving the shortcomings of the conventional tire condition sensing apparatuses.